This invention relates to a fluid-operated cylinder-type actuator, and more particularly to a dual actuator cylinder assembly such as for use in a vacuum packaging apparatus and method.
Cylinder-type actuators are commonly used for providing movement of a component from one position to another. Actuators of this type typically are in the form of a cylinder assembly having a cylinder body defining an internal passage or cavity within which a piston is mounted. The piston is reciprocably moved within the cavity of the cylinder body by selectively supplying pressurized fluid to one side of the piston and exhausting fluid from the opposite side. A rod is connected at an inner end to the piston. The outer end of the rod extends through an end wall of the cylinder body, and is connected to the component that is to be moved from one position to another in response to operation of the cylinder assembly.
In certain applications, it is necessary to actuate two different components that are located closely adjacent each other. For example, the vacuum head of a vacuum packaging apparatus includes a movable seal bar for sealing a vacuum packaging receptacle, and a movable knife member for severing an end portion of the receptacle outwardly of the seal. The seal bar and the knife member are located in close proximity to each other, and are moved between extended and retracted positions independently of each other. In the prior art, it has been necessary to use two separate cylinder assemblies, which can be difficult to mount due to space requirements. In addition, it is necessary to purchase and install the two separate actuators, which increases cost and adds to the time and complexity of assembly.
It is an object of the present invention to provide a cylinder-type actuator that is capable of providing movement of two different components, such that the components can be moved between two different positions independently of each other. It is another object of the invention to provide a dual cylinder-type actuator arrangement that is well suited for use in a vacuum head of a vacuum packaging apparatus, for providing movement of components such as a seal member and a knife member between extended and retracted positions. It is another object of the invention to provide a cylinder-type dual actuator that has a compact configuration and which can be easily mounted and installed. Yet another object of the invention is to provide such a cylinder-type dual actuator which is relatively simple in its components and construction, yet which provides highly satisfactory and effective operation in actuating separate but adjacent components. Yet another object of the invention is to provide a cylinder-type actuation method for moving two different components between two positions, such as an extended position and a retracted position.
In accordance with the present invention, a dual actuator cylinder assembly includes a cylinder body defining first and second axially aligned and separated internal cavities, which extend along aligned longitudinal axes, in combination with a first piston movably mounted in the first internal cavity for movement along the longitudinal axis of the first internal cavity, and a second piston movably mounted in the second internal cavity for movement along the longitudinal axis of the second internal cavity. A first actuator rod arrangement has an inner end interconnected with the first piston and an outer end located exteriorly of the cylinder body, and a second actuator rod arrangement has an inner end interconnected with the second piston and an outer end located exteriorly of the cylinder body. Movement of the first piston within the first internal cavity and movement of the second piston within the second internal cavity causes movement of the first and second actuator rod arrangements, respectively, in an axial direction along the longitudinal axes of the first and second internal cavities. The first and second pistons are movable within the respective first and second internal cavities independently of each other, to provide independent movement of the respective first and second actuator rod arrangements independently of each other. Representatively, the dual actuator cylinder assembly may be incorporated in a vacuum packaging arrangement that includes a seal member and a knife member, with the outer end of the first actuator rod arrangement being interconnected with the seal member for moving the seal member between an operative sealing position and a retracted position, and the outer end of the second actuator rod arrangement being interconnected with the knife member for moving the knife member between an operative cutting position and a retracted position independently of movement of the sealing member. In this manner, a single cylinder assembly is mounted to the vacuum head of the vacuum packaging arrangement, for providing movement of two components within the interior of the vacuum head between extended and retracted positions.
In one form, the cylinder body defines first and second oppositely facing open ends, and a first end closure member encloses the first open end to define the first internal cavity and a second end closure member encloses the second open end to define the second internal cavity. The first end closure member may be in the form of an end cap and the second end closure member may be in the form of a base member configured to mount the cylinder assembly to a surface, such as to the wall of a vacuum head used in a vacuum packaging apparatus.
The first and second internal cavities are separated by a transverse wall defined by the cylinder body, and have circular cross sections. The first cavity has a diameter greater than the second internal cavity, such that the cylinder body defines an annular surface located outwardly of the second internal cavity that forms a part of the first internal cavity. The first rod arrangement is in the form of a pair of parallel rods that extend through a pair of parallel passages formed in the cylinder body that extend from the annular surface through the cylinder body outwardly of the second internal cavity. Each of the pair of parallel rods defines an outer end located exteriorly of the cylinder body. The second rod arrangement is in the form of a single actuator rod located between the pair of parallel rods and having an outer end located exteriorly of the cylinder body.
The cylinder body and the first piston are configured to define separate first and second actuating volumes on opposite sides of the first piston within the first internal cavity. Similarly, the cylinder body and the second piston are configured to define separate first and second actuating volumes on opposite sides of the second piston within the second internal cavity. Selective introduction and exhaust of pressurized fluid into and out of the actuating volumes controls, movement of the first and second pistons within the first and second cavities.
The invention also contemplates a vacuum head of a vacuum packaging arrangement that includes a seal member and a knife member located within an interior defined by the vacuum head. A dual actuator cylinder assembly as summarized above is secured to the vacuum head, for providing movement of the seal member and the knife member between extended, operative positions and retracted, inoperative positions. The outer end of the second rod is interconnected with the seal member for moving the seal member between the extended sealing position and the retracted position, and the outer end of the first rod is interconnected with the knife member for moving the knife member between an extended cutting position and a retracted position independently of movement of the sealing member.
The invention further contemplates a method of actuating separately movable first and second members for movement between two different positions, substantially in accordance with the foregoing summary.
Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings.